Alkaloid compounds and their use as anti-malarial drugs

ABSTRACT

Anti-malarial alkyloid compounds have the formula:  
                 
 
wherein R 1 -R 11  have various disclosed values or their pharmaceutically acceptable salts, and pharmaceutical compositions containing the same.

The present invention concerns alkaloid compounds and their use as amedicament. These compounds and derivatives are particularly usefulagainst malaria in a prophylactic and/or curative treatment. Therefore,the present invention also concerns pharmaceutical compositionscomprising the new compounds and the use of the compounds in a processfor the preparation of anti-malarial compositions. Furthermore inanother aspect of the invention, it concerns a process of preparation ofthese compounds.

Malaria is a serious health care problem posing a great menace tosociety due to the number of patients infected and the mortality rate ofpatients, as evidenced by about 300 million patients attacked annuallypredominantly in tropical and subtropical regions, causing about 2million deaths in these areas.

Malaria is usually treated by administering chloroquine, pyrimethamine,quinine, proguanil, primaquine, artemisinin compounds, etc. . . . , evencombinations thereof, but effective treatments have become difficultwith these conventional anti-malarial drugs because most of the malarialparasites eventually become resistant to these anti-malarial drugs. Mostof the usual anti-malarial compounds are known to be active at the bloodstage of the parasites but not at the hepatic stage.

Some of the known chemical compounds to treat malaria are not free ofside effects, this rendering their long-term use deleterious in someaspects and limiting the use of these compounds.

There is therefore still a need for compounds having an efficiencyagainst malaria, without their usual drawbacks, and not only at theblood stage but also at the hepatic stage, this conferring to thecompounds a prophylactic effect. Furthermore, there is a need foranti-malarial drugs which are easy to formulate in pharmaceuticalcompositions.

The applicants have now found that some compounds isolated fromStrychnopsis thouarsii and also synthetic derivatives thereof have goodanti-malarial activity, particularly on the hepatic stage (also callexoerythrocytic stage) of Plasmodium, contrary to most of conventionalantimalarial drugs which are only active on the erythrocytic cycle.

JP 62-263158 describes sinoccoculine as an anti-tumoral active agent andJP 62-289 565 describes tetracyclic alkaloids and their anti-tumoralactivity, the compounds being extracted from Cocculus sarmentosus orCocculus trilobus.

The present invention thus concerns the use of the compounds of formulaI or II below and their derivatives as medicaments, particularly asanti-malarial compounds.

Amongst them, most are new. In another aspect, the invention concernschemical compounds having the formula

wherein

-   -   R₁ is H or OC_(i)H_(2i+1) with i between 0 and 6;    -   R₂ is H or OC_(j)H_(2j+1) with j between 0 and 6;    -   R₃ is H or OC_(k)H_(2k+1) with k between 0 and 6;    -   R₄ is H or OH;    -   R₅ is OH or OC_(m)H_(2m+1) with m between 1 and 6 or an acetoxy        group or an oxo group;    -   R₆ is OH or OC_(n)H_(2n+1) with n between 1 and 6 or an acetoxy        group or an oxo group;    -   R₇ is OC_(p)H_(2p+1) with p between 0 and 6;    -   R₈ and R₉ may be similar or different and represent H or        OC_(q)H_(2q+1) with q between 0 and 6, or Hal where Hal is Cl,        Br, F or I, or form together a covalent bond whereby the bond is        a double bond or form with an oxygen atom an ether bond (epoxy        group);    -   R₁₀ is H or C_(r)H_(2r+1) with r between 1 and 12 or an        unsaturated alkyl group or a cycloalkyl group (tri- to hexa-)        unsaturated or not, with or without heteroatoms; or an aromatic        or a polycyclic aromatic group with or without heteroatoms; or        C_(s)H_(2s)-A with s between 1 and 12 and whereby A is a        saturated or (tri- to hexa-) unsaturated cycloalkyl group, with        or without heteroatoms or an aromatic or a polycyclic aromatic        group with or without heteroatoms or A is C₆H_(5−t)-(Hal)_(t)        with t between 1 to 5 or C₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u        between 1 to 5 and v between 0 and 6; or R₁₀ represents two        substituents similar or different rendering the nitrogen atom        quaternized, or an oxygen atom (nitrone group) and in which case        the bond between the nitrogen atom and C₉ is a double bond; or        R₁₀ represents CH₂CH₂[OCH₂CH₂]_(w)OCH₂CH₂—B with w between 0 and        10 and where B is OH, O-D or NH-D where D is a C₁-C₁₂ alkyl        group bearing an electrophilic function such as an        isothiocyanate;    -   R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Hal        where Hal is Cl, Br, F or I; or an acetoxy group or a sulfonate        ester group or an oxo group;    -   or R₁₀ and R₁₁ may represent an isoalkylidene group;        or        wherein R₁, R₂, R₃, R₅, R₆, R₇, R₈ and R₉ are defined as above,    -   R₄ is H or OH or OC_(l)H_(2l+1) with l between 2 and 6;    -   R₁₀ is C_(y)H_(2y) with y between 1 and 12 or        CH₂CH₂[OCH₂CH₂]_(z)OCH₂CH₂ with z between 0 and 10; and

-   R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Hal where    Hal is Cl, Br, F or I; or an acetoxy group or a sulfonate ester    group or an oxo group;

-   and all stereoisomers and optical isomers thereof,

-   with the proviso that in formula (I) (1) R₂ is not H or alcoxy when    R₃ is OH or alcoxy and R₄ is H or OH and R₅ and R₆ are OH or acyloxy    and R₇ is OCH₃ and R₈ and R₉ represent a double bound and R₁ is H;    and (2) R₁ is not H when R₂ is H and R₃ and R₇ are OCH₃, R₄, R₅ and    R₆ are OH and R₈ and R₉ represent a double bound and R₁₀ is H, and    particularly with the proviso that in formula (I) (1) R₂ is not H or    alcoxy when R₃ is OH or alcoxy and R₄ is H or OH and R₅ and R₆ are    OH or acyloxy and R₇ is OCH₃ and R₈ and R₉ represent a double bound    and R₁, R₁₀ and R₁₁ are H; and (2) R₁ is not H when R₂ is H and R₃    and R₇ are OCH₃, R₄, R₅ and R₆ are OH and R₈ and R₉ represent a    double bound and R₁₀ and R₁₁ are H, which are known from JP    62-263158 and JP 62-289565.

In the following, the proviso is defined in that, in the compounds offormula I, (1) R₂ is not H or alcoxy when R₃ is OH or alcoxy and R₄ is Hor OH and R₅ and R₆ are OH or acyloxy and R₇ is OCH₃ and R₈ and R₉represent a double bound and R₁ is H; and (2) R₁ is not H when R₂ is Hand R₃ and R₇ are OCH₃, R₄, R₅ and R₆ are OH and R₈ and R₉ represent adouble bound and R₁₀ is H, but also in that in formula (I) (1) R₂ is notH or alcoxy when R₃ is OH or alcoxy and R₄ is H or OH and R₅ and R₆ areOH or acyloxy and R₇ is OCH₃ and R₈ and R₉ represent a double bound andR₁, R₁₀ and R₁₁ are H; and (2) R₁ is not H when R₂ is H and R₃ and R₇are OCH₃, R₄, R₅ and R₆ are OH and R₈ and R₉ represent a double boundand R₁₀ and R₁₁ are H.

Particularly, the invention concerns the compounds of formula I with theabove proviso and the use of compounds of formula I without the provisofor their antimalarial activity. Amongst them, the preferred compoundsare those wherein R₈ and R₉ form a double bound, and R₁ and R₂ are H,and particularly the compounds wherein R₁₁ is OH.

According to an aspect of the invention, R₁₀ can represent H orC_(r)H_(2r)-A with r between 1 and 12 and whereby A is H or a cycleC_(s)H_(2s−l) with s between 3 and 6 or an aromatic cycle or an aromaticpolycycle or an aromatic cycle substituted as C₆H_(5−t)-(Hal)_(t) with tbetween 1 to 5 and where Hal is Cl, Br, F or I, or asC₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u between 1 to 5 and v between 0 to6, or as C₆H_(5−w)—(NH₂)_(w) with w between 1 to 2; or R₁₀ representstwo substituents similar or different rendering the nitrogen atomquaternized, or an oxygen atom; or R₁₀ representsCH₂—CH₂—[O—CH₂—CH₂]_(x)O—CH₂—CH₂—B with x between 0 and 10 and whereby Bis H or OH or NH₂ or N═C═S.

The preferred compounds are described hereafter namely in the examplesand the detailed description.

More particularly, the invention thus concerns4,6,7,10-tetrahydroxy-8,14-didehydro-3,8-dimethoxymorphinan and itsderivative N-methyl-, N-propyl-, N-4-methoxybenzyl-, N4-hydroxybenzyl-,N-4-bromobenzyl- or N-cyclopentyl--4,6,7,10-tetrahydroxy-8,14-didehydro-3,8-dimethoxy-morphinan, as wellas their pharmaceutically acceptable salts, and their optical isomersincluding racemates, and more particularly the isomers having theoptical configuration (6S, 7S, 9R, 10R, 13S).

More particularly, the invention concerns

and the use of (2)

as anti-malarial compounds.

Furthermore, the invention concerns pharmaceutical compositionscontaining the compounds of formula I or II as above defined andstereoisomers and optical isomers and pharmaceutically acceptable saltsthereof as an active agent together with an pharmaceutically acceptablevehicle, particularly an aqueous vehicle.

It also concerns pharmaceutical compositions comprising a compound offormula I or formula II as above defined, without the proviso togetherwith at least one second anti-malarial compound and a pharmaceuticallyacceptable vehicle.

It also concerns the use of these compounds for the preparation of apharmaceutical composition useful in the treatment of malaria, saidcomposition comprises at least a compound of formula I or II without theproviso and another anti-malarial compound.

The invention further concerns the use of the compounds of formula I orII without the proviso and all the stereoisomers and optical isomersthereof, for the preparation of a pharmaceutical composition useful inthe prophylactic or curative treatment of malaria.

According to a further aspect, the invention concerns pharmaceuticalcompositions comprising an isolated extract of Strychnopsis thouarsiihaving an anti-malarial activity.

It also concerns pharmaceutical compositions comprising an isolatedextract of Strychnopsis thouarsii and at least a compound of formula Ior II and a pharmaceutically acceptable vehicle.

The invention also concerns the use of an isolated extract ofStrychnopsis thouarsii in the preparation of a pharmaceuticalcomposition comprising at least said extract of Strychnopsis thouarsiiand a pharmaceutically acceptable vehicle, the composition being usefulin a prophylactic or curative treatment of the malaria.

The compounds of the invention have an anti-malaria activityparticularly drawn to the hepatic stage, which corresponds to thepassage of the parasite into the liver and to the infection of thehepatic cells in which the parasites develop to form the hepaticschizonts which, when they are mature (for example in the case of P.falciparum on the 6^(th) day after penetration of the sporozoites)release hepatic merozoites by bursting. The third stage is characterizedby the infection of the blood erythrocytes by the asexual forms(merozoites) of the parasite; this erythrocytic stage of developmentcorresponds to the pathogenic phase of the disease. The fourth stagecorresponds to the formation of the forms with sexual potential (orgametocytes) which will become extracellular sexual forms or gametes inthe mosquito. The second stage is also called the exoerythrocytic stageof Plasmodium.

The only known and practically used molecules that are active againstthe hepatic stage are primaquine and atovaquone.

Their use is however limited due to the very toxic nature of primaquine,and due to the rapid development of resistance for atovaquone which istherefore only used in combination with other anti-malarial drugs.

The compounds of the invention are particularly useful for prophylacticand curative treatment of the hepatic stage of malaria. Furthermore, thecompounds of the present invention are shown to kill parasites justafter transmission by the infected mosquitoes and before it becomespathogenic by multiplication in the red blood cells. The inventioncompounds are therefore especially useful for antimalarial prophylaxisparticularly as compared with the usual treatments.

Decoction and methanolic extract of the plant were evaluated for theirin vitro antimalarial activity through inhibition of Plasmodium growthin murine and human hepatocytes, according to tests as described below.

A bioassay-guided fractionation of the plant extract, linking this invitro test to chromatographic separation techniques was carried out andled to the isolation of active compounds, as described below.

The invention therefore also encompasses isolated extracts of bark orleaves of the plants described therein for use in a pharmaceuticalcompositions.

The pharmaceutical compositions of the present invention contain apharmaceutically acceptable carrier in addition to the inventioncompound(s). The pharmaceutically acceptable carrier depends on thedosage form.

One of the advantages of the invention compounds is theirbio-availability. Their solubility in water and aqueous vehicles is amajor advantage.

Amongst the pharmaceutically acceptable vehicle, aqueous vehicle arepreferred.

When the pharmaceutical compositions are used for oral administration,they may appropriately contain pharmaceutically acceptable carriersincluding binders such as dicalcium phosphate; disintegrants such assucrose; dyes; and perfumes such as orange flavor; and solvents such aswater, ethanol and glycerol.

When pharmaceutical compositions of the present invention are injectablecompositions, suitable pharmaceutically acceptable carriers includesterilized water, isotonic saline and pH buffers. Alternatively,injectable compositions of the present invention may be sterilizedpowder compositions or lyophilized powder compositions that can be usedby simple dissolution in sterilized water. Injectable pharmaceuticalcompositions of the present invention may contain sugars (glucose,mannitol and dextran, etc.), polyhydric alcohols (glycerol, etc.), andinorganic salts (sodium salts and magnesium salts, etc.).

When pharmaceutical compositions of the present invention areadministered by intravenous injection or infusion, they may containnutrients such as glucose, vitamins, amino acids and lipids.

Pharmaceutical carriers to be added to dosage forms for otheradministration modes such as nasal administration, inhalation andtransdermal administration are also well-known to those skilled in theart.

When pharmaceutical compositions of the present invention are orallyadministered, they may be in the form of controlled- orsustained-release formulations. Well-known sustained-releaseformulations include ordinary sustained- or controlled-releaseformulations such as gel-coated formulations and multicoatedformulations as well as site-specific delivery formulations (e.g., burstrelease at pyloric regions or effervescent delivery to the duodenum).Oral compositions include, for example, tablets, pills, capsules,ampoules, sachet, elixir, suspensions, syrups, etc.

The dosage forms and pharmaceutical carriers mentioned above aredescribed in Remington's Pharmaceutical Sciences, 16^(th) ed. (1980),Mack Publishing Company, which is incorporated herein by reference.

Pharmaceutical compositions or unit dose systems of the presentinvention can be administered via various other routes such astransmucosal (sublingual, nasal, buccal), enteral, dermaladministration, suppositories or intravenous infusion. Theseadministration modes depend on the amount of the active compound to beadministered, the condition of the patient and other factors.

Among these administration modes, oral administration is especiallypreferred as well as any mode where the use of aqueous vehicle is ofinterest.

According to the invention the inventive compound is present in anamount of between 0.001 and 50% by weight of the pharmaceuticalcomposition.

When present in combination with a second anti-malarial compound or asan enhancer of the anti-malarial activity of another anti-malarialcompound, the inventive compound is present in an amount between 0.0001and 20% by weight of the pharmaceutical composition.

In the present invention, the effective amount of inventive compoundused for the treatment of malaria is normally 1-1,000 mg/kg weightdaily, preferably 5-500 mg/kg weight daily depending on the age, bodyweight and condition of the patient and the administration mode.

Apart from their obtention by the extraction process, the compounds ofthe invention can be obtained by synthesis. As it appears from thefollowing examples, the derivatives of (1) and (2) can be preparedaccording to usual chemical procedures. Particularly alkylationprocedures are carried out on products (1) and (2) under suitablealkylation conditions with the corresponding suitable alkylating agents.For example suitable alkylating agents are the corresponding aldehydesor dialdehydes. Suitable conditions can be reductive alkylationconditions.

Furthermore, oxidation and subsequent alkylation can be carried out byusual procedures, and protection of the substituants previouslyperformed, if necessary.

In the following examples, stem bark has been treated to extract thecompounds from the plant. However, other parts of the plant might betreated, as well as other species able to produce similar extracts. Theleaves of Strychopsis thouarsii can also be used, as well as otherplants and species. The person skilled in the art can adapt theseparation process to the species or part of the plant to be treated.

FIG. 1 is a graph indicating the percentage parasitemia dayspost-infection. The control group is indicated by an •, while thetreated group with compound (1) is indicated with ⋄.

PREPARATION EXAMPLES Example 1 Extraction Process

500 g powdered Strychnopsis thouarsii stem bark was soaked understirring in MeOH at room temperature for six days, according to thefollowing procedure.

Each 24 hours, the solute was filtrated and the solid residue wastreated with 2 l MeOH. The resulting six solutes were pooled andevaporated to dryness under reduced pressure, providing 22 g ofmethanolic extract.

This extract was dissolved in 2 l H₂O and centrifugated at 10,000 rpmfor 1 hour. A residue of 10 g was removed, while the supernatant waspartitioned three times between H₂O and CH₂Cl₂ (500 mL).

The resulting aqueous extract of 11.7 g was chromatographed on areversed phase silica gel column (RP-2), eluted with a discontinuousgradient of H₂O-MeOH in the proportion of (100-0, 90-10, 80-20, 0-100).

The fractions were pooled according to their TLC profiles into 3fractions F1 to F3.

The fraction F1 (9.4 g) was further separated on a silica gel column,eluted with CH₂Cl₂-MeOH—NH₄OH (85-15-0.5) leading to 10 fractions F1-1to F1-10.

The fraction F1-6 was determined to be the most active amongst theobtained fraction, by an evaluation of the biological activity carriedout according to the method as described below.

Example 2 Isolation of Compounds (1) and (2)

Compound(1)=4,6,7,10-tetrahydroxy-8,14-didehydro-3,8-dimethoxy-morphinanC₁₈H₂₃NO₆

Compound (2)=4,6,7-trihydroxy-8,14-didehydro-3,8-dimethoxy-morphinan(Sinococuline or FK1000) [CAS Registry Number: 109351-36-2] C₁₈H₂₃NO₅

An aliquot of fraction F1-6 (0.850 g) was chromatographed on a sephadexgel column (LH-20) eluted with MeOH, leading to 4 fractions, F1-6-1 toF1-6-4.

The fraction F1-6-3 (0.368 g) was purified on a silica gel column elutedwith CH₂Cl₂-MeOH—NH₄OH (87-13-1), leading to 6 fractions, F1-6-3-1 toF1-6-3-6.

The fraction F1-6-3-4 (0.122 g) was shown to be a mixture of the twocompounds (1) and (2).

An aliquot of F1-6-3-4 (0.045 g) was further submitted to a preparativesilica gel TLC migrating in CHCl₃—NH(C₂H₅)₂ (70-30), leading to 2fractions, F1-6-3-4-1 (0.01 g) and F1-6-3-4-2 (0.028 g).

The first fraction was submitted to a silica gel column filtration withCH₂Cl₂-MeOH—NH₄OH (70-30-3), providing pure compound (2) (0.004 g),while the second fraction, under the same conditions, afforded purecompound (1) (0.019 g).

Example 3 Isolation of Compounds (1) and (2)

An aliquot of fraction F1-6 (0.22 g) was straightly subjected to apreparative silica gel TLC migrating in CHCl₃-MeOH—NH₄OH (75-25-3.5),providing compound (1) (0.04 g), while bands corresponding to less polarproducts were pooled and submitted to a second preparative TLC migratingin CHCl₃-MeOH—CH₃COOH—H₂O (75-18-4-3), leading to 3 fractions, F1-6-1′to F1-6-3′.

The fraction F1-6-1′ (0.012 g) was subjected to a silica gel columnfiltration with CH₂Cl₂-MeOH—NH₄OH (90-10-1), providing pure compound (2)(0.004 g).

Example 4 Analytical Data of Compounds (1) and (2)

1) Compound (1)

a) NMR data of (1) in CD₃OD and its attribution by 2D NMR (400 MHz):Carbon number δ H (multiplicity, J in Hz) δ C  1 6.86 (d, 8.4) 121.93  26.90 (d, 8.4) 110.67  3 — 149.18  4 — 145.07  5 ₁ 2.95 (dd, 3.3, 13.4)36.51  5 ₂ 2.19 (dd, 13.4, 13.4)  6 3.86 (m, 2.7, 3.3, 13.4) 68.60  74.28 (d, 2.7) 66.91  8 — 148.49  9 4.33 (d, 2.2) 53.13 10 4.53 (d, 2.2)73.31 11 — 132.91 12 — 129.78 13 — 40.05 14 — 121.09 15 ₁ 1.99 (dd, 3.6,12.5) 37.50 15 ₂ 1.84 (ddd, 4.7, 12.5, 12.5) 16 ₁ 2.64 (dd, 4.7, 14.3)40.85 16 ₂ 2.42 (ddd, 3.6, 14.3) 3-OCH₃ 3.86 (s) 56.57 8-OCH₃ 3.69 (s)57.06

b) Physico-chemical data of (1)

Mass Spectroscopy (ESI-TOF⁺): m/z 350.1 [M+H]⁺

Mass calculated for C₁₈H₂₄NO₆: 350.1604

High Resolution MS (DCI⁺): m/z 350.1604 [M+H]⁺

UV (λ_(max)nm (ε), MeOH): 282 (3318), 242_(sh) (9926), 207 (57483)

[α]²⁰ _(D) −46° (c 0.5, MeOH)

Circular Dichroism (λext_(nm), θ): (216, +66324), (227, −15949), (242,+16864)

(c=1.15×10⁻³ M, MeOH)

2) Compound (2)

a) NMR data of (2)

¹H-NMR (300 MHz, CD₃OD): δ 6.85 (d, 1H, J=8.3 Hz), 6.62 (dd, 1H, J=1.2,8.3 Hz), 4.96 (dd, 1H, J=1.7, 6.2 Hz), 4.39 (dd, 1H, J=1.1, 3.1 Hz),3.87 (ddd, 1H, J=3.1, 3.9, 13.5 Hz), 3.84 (s,3H), 3.78 (s, 3H), 3.31(ddd, 3H, J=1.2, 6.2, 19.1 Hz), 3.14 (dd, 1H, J=4.6, 13.1 Hz), 3.10 (dd,1H, J=1.7, 19.1 Hz), 3.03 (ddd, 1H, J=1.1, 3.9, 13.5 Hz), 2.84 (ddd, 1H,J=4.1, 13.1, 13.2 Hz), 2.24 (dd, 1H, J=13.5, 13.5 Hz), 2.19 (dd, 1H,J=4.1, 13.2 Hz), 2.06 (ddd, 1H, J=4.6, 13.2, 13.2 Hz)

¹³C-NMR (300 MHz, CD₃OD): δ 33.53, 34.08, 36.0, 38.46, 40.67, 47.96,56.22, 56.67, 65.38, 68.11, 111.30, 113.92, 119.48, 127.90, 128.56,145.79, 148.09, 150.66

The NMR data of (2) were similar to those previously described inliterature [1, 2].

b) Physico-chemical data of (2)

Mass Spectroscopy (ESI-TOF⁺): m/z 334.1 [M+H]⁺

Mass calculated for C₁₈H₂₄NO₅: 334.1654

High Resolution MS calculated for C₁₈H₂₃NO₅: 334.1655

UV (MeOH) λ_(max)nm (ε): 282 (2856), 242_(sh) (6984), 207 (59602)

[α]²⁰ _(D) −143° (c 0.25, MeOH) cf. [3] [α]²⁰ _(D) −137.4° (c 0.12,MeOH)

Circular Dichroism (λext_(nm), θ): (216, +63340), (227, −15231), (242,+16105)

(c=1.20×10⁻³ M, MeOH)

cf. [1] CD (λext_(nm), θ): (238, +62100) (c=9.67×10⁻⁵ M, MeOH)

3) Stereochemistry of Compounds (1) and (2):

Specific rotation values of compound (2) and sinococuline were closelythe same.

Compounds (1) and (2) showed the same Nuclear Overhauser EffectSpectroscopY (NOESY) correlations (cf. table 1) as sinococuline.Consequently compounds (1) and (2) have been assigned with the samerelative configuration (6S*, 7S*, 9R*, 13S*) as sinococuline.

Moreover, compounds (1) and (2) exhibited similar CD spectra (positivemaxima at 216 nm and 242 nm, negative maximum at 227 nm), in agreementwith this of sinococuline described in literature, allowing us toconclude that the absolute configuration of compound (1) and compound(2) is (6S, 7S, 9R, 10R, 13S) and (6S, 7S, 9R, 13S) respectively. TABLE1 NOESY (2D-NMR, 400 MHz, MeOH) Compound (1) Compound (2) Proton n°Correlated protons Correlated protons  1 H10 H2, H10₁, H10₂  2 3-OCH₃H1, 3-OCH₃  3 — —  4 — —  5 ₁ H15₁, H5₂, H6, H7 H5₂, H6  5 ₂ H5₁, H6H5₁, H6  6 H15₂, H5₂, H5₁, H7 H5_(1,) H5₂, H7, H15₂  7 8-OCH₃, H63-OCH₃, H5₂, 8-OCH₃  8 — —  9 8-OCH₃, H10 8-OCH₃, H10₁, H10₂ 10 ₁ H16₂,H9, H1 H1, H9, H10₂ 10 ₂ H1, H9, H10₁ 11 — — 12 — — 13 — — 14 — — 15 ₁H15₂, H16₂, H16₁, H5₁ H5₁, H15₂, H16₂ 15 ₂ H15₁, H16₁, H6 H6, H15₁, H16₁16 ₁ H15₁, H15₂, H16₂ H15₁, H15₂, H16₂ 16 ₂ H15₁, H16₁, H10 H15₁, H16₁3-OCH₃ H2 H2 8-OCH₃ H7, H9 H7

Example 5 N-methyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (3) C₁₉H₂₅NO₆

1) Preparation of Compound (3)

To a solution of (1) (10.9 mg, 0.031 mmol) in 1 mL MeOH was added 100 μlof a solution of formaldehyde (37% in water). After stirring for 1 hourat room temperature, 3 mg of NaBH₄ was added and the mixture was stirredfor additional 3 hours.

After removal of the solvent under reduced pressure, the residue wasacidified with 1N HCl, then basified with 20% aqueous NH₄OH and wasfurther submitted to a silica gel column eluted with CH₂Cl₂-MeOH—NH₄OH(85-15-1), leading to compound (3) as a white solid (8 mg, 0.022 mmol),71% yield.

2) Analytical Data of (3)

¹H-NMR (300 MHz, CD₃OD): δ 6.90 (d, 1H, J=8.4 Hz), 6.83 (d, 1H, J=8.4Hz), 4.70 (d, 1H, J=2.2 Hz), 4.30 (dd, 1H, J=1.3, 3.4 Hz), 4.21 (d, 1H,J=2.2 Hz), 3.88 (m,1H, J=3.4, 4.1, 13.8 Hz), 3.87 (s, 3H), 3.70 (s, 3H),2.98 (ddd, 1H, J=1.3, 4.1, 13.8 Hz), 2.51 (dd, 1H, J=3.3, 12.4 Hz), 2.47(s, 3H), 2.26 (m, 1H, J=2.9, 12.4, 12.9 Hz), 2.18 (dd, 1H, J=13.8, 13.8Hz), 1.95 (m, 2H, J=2.9, 3.3, 12.9 Hz)

Mass Spectroscopy (ESI-TOF⁺): m/z 364.1 [M+H]⁺

Mass calculated for C₁₉H₂₆NO₆: 364.1760

High Resolution MS (DCI⁺): m/z 364.1764 [M+H]⁺

[α]²⁰ _(D) −41° (c 0.5, MeOH)

Example 6 N-propyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (4) C₂₁H₂₉NO₆

1) Preparation of Compound (4)

To a solution of (1) (3.05 mg, 0.0087 mmol) in 300 μl MeOH, was added 1μl, 0.014 mmol of propionaldehyde and 0.6 mg, 0.0095 mmol of sodiumcyanoborohydride NaBH₃CN. The mixture was stirring for 4 hours at roomtemperature.

After removal of the solvent under reduced pressure, the residue wasacidified with HCl 1N, then basified with 20% aqueous NH₄OH and wassubmitted to a preparative TLC eluted twice with CH₂Cl₂-MeOH—NH₄OH(90-10-1) to provide (4) as a white solid (2.3 mg, 0.0059 mmol), 68%yield.

2) Analytical Data of (4)

¹H-NMR (300 MHz, CD₃OD): δ 6.99 (d, 1H, J=8.4 Hz), 6.96 (d, 1H, J=8.4Hz), 4.82 (d, 1H, J=1.9 Hz), 4.72 (s, 1H), 4.37 (d, 1H, J=3.3 Hz), 3.92(m, 1H), 3.89 (s, 3H), 3.78 (s, 3H), 3.05 (m, 4H), 2.66 (m, 2H), 2.27(dd, 1H, J=13.5, 13.5 Hz), 2.11 (dd, 1H, J=3.9, 12.3 Hz), 1.77 (m, 2H,J=2.2, 7.3, 7.3 Hz), 1.02 (t, 3H, J=7.3 Hz)

Mass Spectroscopy (ESI-TOF⁺): m/z 392.2 [M+H]⁺

Mass calculated for C₂₁H₃₀NO₆: 392.2073

High Resolution MS (DCI⁺): m/z 392.2064 [M+H]⁺

[α]²⁰ _(D) −18° (c 0.1 MeOH)

Example 7 N-4-methoxybenzyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (5) C₂₆H₃₁NO₇

1) Preparation of Compound (5):

To a solution of (1) (5.7 mg, 0.016 mmol) in 500 μl MeOH, was added 200μl, 1.6 mmol of anisaldehyde. After stirring for 1 hour at roomtemperature, 3 mg of NaBH₄ was added and the mixture was stirred foradditional 3 hours at room temperature.

After removal of the solvent under reduced pressure, the residue wasacidified with HCl 1 N, then basified with 20% aqueous NH₄OH and wassubmitted to a preparative TLC, eluted twice with CH₂Cl₂-MeOH—NH₄OH(90-10-1.5) to provide (5) as a white solid (3.0 mg, 0.0064 mmol), 40%yield.

2) Analytical Data of (5)

¹H-NMR (300 MHz, CD₃OD): δ 7.47 (d, 2H, J=8.6 Hz), 7.0 (d, 2H, J=8.6Hz), 6.98 (d, 1H, J=8.4 Hz), 6.93 (d, 1H, J=8.4 Hz), 4.88 (s, 1H), 4.71(s, 1H), 4.40 (d, 1H, J=2.8 Hz), 4.25 (s, 2H), 3.99 (m, 1H), 3.88 (s,3H), 3.83 (s, 3H), 3.77 (s, 3H), 3.06 (m, 2H, J=3.6, 3.9, 12.5, 13.6Hz), 2.75 (dd, 1H, J=2.1, 12.5 Hz), 2.28 (ddd, 1H, J=3.2, 13.6, 13.6Hz), 2.20 (dd, 1H, J=3.9, 13.2 Hz), 2.07 (dd, 1H, J=2.1, 13.2 Hz)

MS (ESI-TOF⁺): m/z 470.2 [M+H]⁺

Mass calculated for C₂₆H₃₂NO₇: 470.2179

High Resolution MS (DCI⁺): m/z 470.2170 [M+H]⁺

[α]²⁰ _(D) −12° (c 0.1, MeOH)

Example 8 N-4-hydroxybenzyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (6) C₂₅H₂₉NO₇

1) Preparation of Compound (6)

To a solution of (1) (4.85 mg, 0.014 mmol) in 500 μl of MeOH was added4-hydroxy-benzaldehyde (1.7 mg, 1 eq). After stirring for 4 hours atroom temperature, 0.9 mg, 1 eq of NaBH₃CN was added and the mixture wasstirred for additional 3 hours at room temperature.

After removal of the solvent under reduced pressure, the residue wasacidified with HCl 1N, then basified with 20% aqueous NH₄OH and wassubmitted to a preparative TLC, eluted twice with CH₂Cl₂-MeOH—NH₄OH(90-10-1) to provide (6) as a white solid (3.5 mg, 0.0077 mmol), 55%yield.

2) Analytical Data of (6)

¹H-NMR (300 MHz, CD₃OD): δ 7.29 (d, 2H, J=8.6 Hz), 6.96 (d, 1H, J=8.4Hz), 6.91 (d, 1H, J=8.4 Hz), 6.82 (d, 2H, J=8.6 Hz), 4.79 (s, 1H), 4.57(d, 1H, J=1.6 Hz), 4.37 (d, 1H, J=3.3 Hz), 4.01 (d, 2H, J=8.1 Hz), 3.94(ddd, 1H, J=3.7, 3.7, 12.9 Hz), 3.87 (s, 3H), 3.72 (s, 3H), 3.02 (dd,1H, J=4.1, 13.5 Hz), 2.88 (d, 1H, J=12.6 Hz), 2.59 (ddd, 1H, J=3.7,12.6, 12.6 Hz), 2.25 (dd, 1H, J=13.5, 13.5 Hz), 2.12 (ddd, 1H, J=4.5,12.6, 12.6 Hz), 2.01 (d, 1H, J=12.6 Hz)

Mass Spectroscopy (ESI-TOF⁺): m/z 456.2 [M+H]⁺

Mass calculated for C₂₅H₃₀NO₇: 456.2022

High Resolution MS (DCI+): m/z 456.2018 [M+H]⁺

[α]²⁰ _(D) −10° (c 0.03, MeOH)

Example 9 N-4-bromobenzyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (7) C₂₅H₂₈NO₆Br

1) Preparation of Compound (7)

To a solution of (1) (3.3 mg, 0.0095 mmol) in 300 μl MeOH was added 2mg, 0.011 mmol of 4-bromo-benzaldehyde and 3 mg of NaBH₃CN. The mixturewas stirred 20 hours at room temperature.

After removal of the solvent under reduced pressure, the residue wasacidified with HCl 1N, then basified with 20% aqueous NH₄OH and wassubmitted to a preparative TLC eluted twice with CH₂Cl₂-MeOH—NH₄OH(95-5-0.5) to provide (7) as a white solid (3.0 mg, 0.0058 mmol), 61%yield.

2) Analytical Data of (7)

¹H-NMR (300 MHz, CD₃OD): δ 7.51 (d, 2H, J=8.4 Hz), 7.35 (d, 2H, J=8.4Hz), 6.92 (d, 1H, J=8.4 Hz), 6.88 (d, 1H, J=8.4 Hz), 4.78 (d, 1H, J=3.4Hz), 4.74 (s, 2H), 4.73 (d, 1H, J=2.2 Hz), 4.32 (d, 1H, J=1, 3.4 Hz),3.93 (ddd, 1H, J=2.9, 3.4, 13.5 Hz), 3.88 (s, 3H), 3.68 (s, 3H), 3.0(dd, 1H, J=2.9, 13.5 Hz), 2.66 (m, 1H, J=4.6, 12.1 Hz), 2.46 (ddd, 1H,J=3.9, 12.1, 12.1 Hz), 2.21 (dd, 1H, J=13.5, 13.5 Hz), 2.05 (ddd, 1H,J=4.6, 12.6, 12.6 Hz), 1.94 (ddd, 1H, J=1.9, 3.9, 12.6 Hz)

Mass Spectroscopy (ESI-TOF⁺): m/z 519.1 and 521.1 [M+H]⁺

Mass calculated for C₂₅H₂₉NO₆Br: 519.1035 and 521.1055

High Resolution MS (DCI⁺): m/z 519.1037 and 521.1058 [M+H]⁺

[α]²⁰ _(D) −0.5° (c 0.5, MeOH)

Example 10 N-cyclopentyl-4,6,7,10-tetrahydroxy-8,14,didehydro-3,8-dimethoxy-morphinan (8) C₂₃H₃₁NO₆

1) Preparation of Compound (8)

To a solution of (1) (4.95 mg, 0.014 mmol) in 300 μl of MeOH was added 2μl, 0.023 mmol of cyclopentanone and 3 mg of NaBH₃CN. The mixture wasstirred for 6 hours at room temperature.

After removal of the solvent under reduced pressure, the residue wasacidified with 1 N HCl, then basified with 20% aqueous NH₄OH and wassubmitted to a preparative TLC eluted twice with CH₂Cl₂-MeOH—NH₄OH(90-10-1) to provide (8) as a white solid (4.75 mg, 0.011 mmol), 81%yield.

2) Analytical Data of (8)

¹H-NMR (300 MHz, CD₃OD): δ 6.98 (d, 1H, J=8.4 Hz), 6.94 (d, 1H, J=8.4Hz), 4.83 (s, 1H), 4.71 (s, 1H), 4.37 (d, 1H, J=2.7 Hz), 3.91 (m, 1H),3.88 (s, 3H), 3.78 (s, 3H), 3.21 (d, 1H, J=12.6 Hz), 3.05 (dd, 1H,J=3.5, 14.3 Hz), 2.27 (m, 2H, J=12.6, 14.3 Hz), 2.16 (m, 1H), 1.86 (m,4H), 1.65 (m, 6H)

Mass Spectroscopy (ESI-TOF⁺): m/z 418.2 [M+H]⁺

Mass calculated for C₂₃H₃₂NO₆: 418.2230

High Resolution MS (DCI⁺): m/z 418.2239 [M+H]⁺

[α]²⁰ _(D) −30° (c 0.03, MeOH)

Evaluation of the Biological Activity of Compounds

Materials and Methods

In vitro Evaluation of the Antimalarial Activity of Plant Extracts andPure Compounds (1)-(8)

A—Murine Model: Hepatic Stage of Plasmodium yoelii yoelii 265BY.

Primary cultures of mouse hepatocytes were isolated from livers of Swissmice which were 6 to 8 weeks old by perfusion with collagenase (1 g/L)and purified through a 60% Percoll gradient.

The hepatocytes were cultured in sterile chambers (Lab-Tek) at the rateof 90,000 cells in 0.3 mL of complete culture medium as definedthereafter per well and incubated overnight at 37° C. under a 4% CO₂atmosphere. The hepatocytes' complet culture medium was Williams' Eculture medium supplemented with 10% of decomplemented foetal calfserum, 1% glutamine, 1% Na pyruvate, 1% of a mixture of insulin,transferrine and selenium, 1% of non-essential amino-acids and with anantibiotic mixture comprising 1% of a solution of penicillin andstreptomycine, 1% augmentin and 2.5 pg/ml flucytosine.

The parasites infecting the hepatocytes; i.e. the sporozoites, wererecovered by dissection of infected anopheles mosquitoes salivaryglands.

After grinding them in a Potter grinder with culture medium, thesuspension was filtered on a 40 μm mesh filter and centrifuged (15,000rpm) at 4° C. for 2 mn. The pellet was reintroduced in the completeculture medium. The sporozoites were then counted in a “Cell Vu” counter(CML) and the concentration was adjusted at 100,000 sporozoites per 70μL, concentration needed for infection.

One day after, the hepatocytes were infected by the above sporozoitesfrom salivary glands of infected anopheles mosquitoes at the rate of100,000 sporozoites per well in the presence or absence of the productto be tested. When the infection had appeared, the medium wassupplemented with 10⁻⁷ M dexamethasone. The products were firstsolubilized in DMSO.

The infected hepatocytes were washed and fed with culture mediumcontaining the test product, 3 hours and then 24 hours after theinfection.

The cultures were stopped by treatment with a cold fixative methanolsolution, 48 hours after the infection.

Parasites obtained in schizont stage were immunomarked firstly, with aserum isolated from BALB/c mice immunized with a recombinant fragmentfrom the N-terminal of the recombinant protein I72 that reacted againstHSP70 of Plasmodium [4] and secondly with an antibody—a mouseanti-immunoglobulin—conjugated to FITC. Evans Blue and DAPI, a nucleicacid marker, were added to the hepatocytes simultaneously. The schizontswere then counted with a fluorescent microscope.

Extracts and purified products exhibiting a significant inhibitioneffect on P. yoelii yoelii 265BY growth in murine hepatocytes weretested on human hepatocyte cultures infected with P. falciparum NF54.

B—Human Model: Hepatic Stage of Plasmodium falciparum NF54

Human hepatocytes were obtained by enzymatic perfusion of fragments ofliver of human adults which were submitted to partial hepatectomy.

The hepatocytes were infected at 24 hours of their culture bysporozoites obtained from salivary glands of P. falciparum infectinganopheles mosquitoes stephensi (Lab. of Pr. W. Eling, Univ. Of Nijmegen,NL).

The culture medium containing the test product was changed 3 hours afterinfection, and then renewed at least, each 24 hours during theexperiment.

The cultures were fixed 5 days after infection, with the same method asdescribed for the murine hepatocytes [5].

The CI₅₀ value (concentration causing 50% of inhibition in the number ofparasites compared to controls wells, non treated) is the mean value of3 independent evaluations through StatView SI Graphics.

In vitro Evaluation of the Cytotoxicity of Plant Extracts and PureCompounds (1)-(8)

The cytotoxicity assays were carried out in 96-well microliter plates,in triplicate, against human carcinoma KB cell line (ATCC CCL-17) (10⁴cells/mL in DMEM medium) and human colon tumor HT29 cell line (ATCCHTB-38) (10⁵ cells /mL in RPMI 1640 medium), both supplemented with 10%foetal calf serum, L-glutamine (2 mM), penicillin G (100 UI/mL),streptomycin (100 μg/mM) and gentamycin (10 μg/mL).

Stock solutions of testing compounds were prepared in H₂O/DMSO (9/1).

After an incubation of 72 hours at 37° C. under a 5% CO₂ atmosphere,0.02% of neutral red in PBS was added.

24 hours later, culture media were eliminated and cell membranes werelysed by addition of 1% of SDS in water.

Cell growth was estimated by colorimetric measurement of stained livingcells, incorporating neutral red. Optical density was determined at 540nm on a Titertek Multiskan photometer.

The CI₅₀ value was defined as the concentration of compound necessary toinhibit the cell growth to 50% of the control.

Results

Table 2 represents in vitro activities of natural compounds (1) and (2)and N-substituted derivatives of (1), compounds (3)-(8), on growthinhibition of P. yoelii yoelii 265 BY in murine hepatocytes and theircytotoxicity on human tumor cell lines.

In Table 2, R represents the group introduced on the nitrogen atom bychemical modification of (1) as defined in formula I.The selectivity index (=ratio between CI₅₀ of cytotoxicity and CI₅₀ ofanti-malarial activity) that was calculated, should the real effect ofthe compounds on Plasmodium parasites with respect to mammalian cells.

Primaquine and atovaquone were tested as references for their inhibitingactivities on hepatic stage of Plasmodium, while 5-fluorouracile andvinblastine were tested as references for their cytotoxic activities onKB and HT29 cells. TABLE 2 CI₅₀ activity Selectivity P. yoelii 265BYCI₅₀ cytotoxicity CI₅₀ cytotoxicity index Compound in μg/mL, KB HT29CI₅₀ KB/CI₅₀ —R₁₀ (μM) in μg/mL, (μM) in μg/mL, (μM) yoelii (1) 1.081.99 ± 1.3 22.0 ± 12.5 1.8 —H [0.15-0.32] 5.7 63.0 3.1 (2) 1.50 1.30 ±0.6 12.24 ± 8.59 0.9 —H [0.25-0.45 3.9 36.8 4.5 (3) 2.09 32.31 ± 7.1 >8015.5 —CH3 [0.87-0.67] 89.0 >220 5.8 (4) 4.93 40.37 ± 13.9 >80 8.2—CH2—CH2—CH3 [0.69-0.60] 103.2 >204 12.6

11.4 [0.75-0.64]24.2 21.23 ± 6.2 45.3 >80 >170 1.9

6.44 [0.92-0.80]14.2 9.53 ± 3.3 20.9 48.96 ± 1.8 107.6 1.5

2.19 [0.92-0.71]4.2 15.81 ± 6.4 30.5 >80 >154 7.3

1.46 [1.01-0.89]3.5 27.64 ± 9.0 66.28 >80 >192 18.9 primaquine 0.16 2.0± 0.9 20.12 ± 2.1 11.7 [0.11-0.28] 7.0 70.51 0.6 Atovaquone 0.021 18.60± 8.7 44.60 ± 10.3 891.2 [0.003-.009] 50.8 122 0.057 5-fluorouracile /0.047 ± 0.03 54.88 ± 2.4 / 0.36 422 Vinbiastine / 0.018 ± 0.006 0.0080 ±0.004 / 0.022 0.0099

Table 3 represents in vitro activities of natural compounds (1) and (2),on P. falciparum NF54 in human hepatocytes. TABLE 3 CI₅₀ activity P.falciparum NF54 in μg/mL, (μM) (1) 1.51 [1.01-0.34] 4.3 (2) 3.36[1.35-0.92] 10.1 

In vivo Evaluation of the Antimalarial Activity of Compound (1)

40 Swiss mice (six week old) have been subjected to the in vivo assay.They have been allotted in two groups:

-   -   a group of 20 mice were fed with compound (1) diluted in sterile        water at a dose of 100 mg/kg four times; 24 hours and 1 hour        before infection, 24 hours and 40 hours after infection during        the hepatic stage period.    -   a control group of 20 mice were fed with sterile water at the        same times.

The infection has been performed by retro-orbital injection of 4,000sporozoites of Plasmodium yoelii yoelii 265BY in 100 μlphospate-buffered saline per mouse.

The parasitemia was monitored from the third day after the infection D3when the parasites are liberated from the liver and enter into the bloodcirculation and each day until the 23rd day D23 after infection. Themonitoring was performed by blood smears taken from the tail vein of themice. The smears were stained with Giemsa and parasited red blood cellswere counted with a microscope.

The parasitemia was calculated according to the following formula:Parasited red blood cell number×100/total red blood cell number.

Results

The following table presents the obtained results. Number of parasitedDays post-infection mice/20 total mice D3 D4 D5 D6 D7 D8 D23 ControlGroup 20/20 20/20 20/20 20/20 20/20 20/20 15/15 Treated group with  0/20 0/20  0/20  1/20  4/20  6/20  6/18 compound (1)

None of the treated mice were parasited at the fifth day after theinfection whereas 100% of the control mice were parasited as soon as thethird day.

In the treated group, the first mouse was parasited at the sixth dayafter infection with a delay of 3 days compared to the control groupmice. At the end of the assay, on the 23^(rd) day, only 6 of the 20treated mice were parasited, whereas 100% of the control mice wereparasited. The results are set forth in FIG. 1.

As a first conclusion the treatment with compound (1) at 100 mg/kgallows a 70% total protection against malaria infection in mice, butalso it allows a minimum 3 days delay for the 30% of treated mice, whichwere not protected.

As a second conclusion, the treatment with compound (1) at 100 mg/kgallows a better survival of mice at D23 in the treated group (90%)compared to the control group (75%).

Furthermore, the mean percentage of parasitemia was lower for miceparasited in the treated group compared to mice parasited in the controlgroup (FIG. 1).

As a third conclusion, the treatment with compound (1) at 100 mg/kgallows a significant decrease of the number of parasited red bloodcells.

The in vivo results confirm the in vitro results concerning theefficiency of compound (1) on the protection against Plasmodium yoelii265BY and Plasmodium falciparum NF54. Compound (1) in oraladministration, protects mice against infection by P. yoelii 265BY(70%), reduces parasitemia, delays apparition of the parasites andimproves mice survival.

This prophylactic treatment differs from the usual treatments whichmainly target the blood forms of the parasite.

REFERENCES

-   [1] Itokawa H., Tsuruoka S., Takeya K., Mori N., Sonobe T., Kosemura    S., Hamanaka T. An Antitumor Morphinane Alkaloid, Sinococuline, from    Cocculus trilobus. Chem. Pharm. Bull., 1987, 35, 1660-1662.-   [2] Deng J.-Z., Zhao S.-X., Miao Z.-C. A Morphinan Alkaloid from    roots of Stephania cepharantha. Phytochemistry, 1992, 31(4),    1448-1450.-   [3] Hitotsuyanagi Y., Nishimura K., Ikuta H., Takeya K., Itokawa H.    Synthesis of Antitumor morphinane Alkaloids, Sinococuline and    6-epi-, 7-epi-, and 6-epi-7-epi-Sinococuline, from Sinomenine. J.    Org. Chem., 1995, 60, 4549-4558.-   [4] Motard A., Marussig M., Renia L., Baccam D., Landau I., Mattei    D., Targett G., Mazier D. Immunization with the malaria heat shock    like protein hsp70-1 enhances transmission to the mosquito. Int.    Immunol., 1995, 7(1), 147-50.-   [5] Mazier D., Beaudoin R. L., Mellouk S., Druilhe P., Texier B.,    Trosper J., Miltgen F., Landau I., Paul C., Brandicourt O., et al.    Complete development of hepatic stages of Plasmodium falciparum in    vitro. Science, 1985, 227(4685), 440-2.

1. Chemical compound having the following formula

wherein R₁ is H or OC_(i)H_(2i+1) with i between 0 and 6; R₂ is H orOC_(j)H_(2j+1) with j between 0 and 6; R₃ is H or OC_(k)H_(2k+1) with kbetween 0 and 6; R₄is H or OH; R₅ is OH or OC_(m)H_(2m+1) with m between1 and 6 or an acetoxy group or an oxo group; R₆ is OH or OC_(n)H_(2n+1)with n between 1 and 6 or an acetoxy group or an oxo group; R₇ isOC_(p)H_(2p+1) with p between 0 and 6; R₈ and R₉ may be similar ordifferent and represent H or OC_(q)H_(2q+1) with q between 0 and 6, orHal where Hal is Cl, Br, F or I, or form together a covalent bondwhereby the bond is a double bond or an ether bond (epoxy group); R₁₀ isH or C_(r)H_(2r+1) with r between 1 and 12 or an unsaturated alkyl groupor a cycloalkyl group (tri- to hexa-) unsaturated or not, with orwithout heteroatoms; or an aromatic or a polycyclic aromatic group withor without heteroatoms; or C_(s)H_(2s)-A with s between 1 and 12 andwhereby A is a saturated or (tri- to hexa-) unsaturated cycloalkylgroup, with or without heteroatoms or an aromatic or a polycyclicaromatic group with or without heteroatoms or A is C₆H_(5−t)-(Hal)_(t)with t between 1 to 5 or C₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u between1 to 5 and v between 0 and 6; or R₁₀ represents two substituents similaror different rendering the nitrogen atom quaternized, or an oxygen atom(nitrone group) and in which case the bond between the nitrogen atom andC₉ is a double bond; or R₁₀ represents CH₂CH₂[OCH₂CH₂]_(w)OCH₂CH₂—B withw between 0 and 10 and where B is OH, O-D or NH-D where D is a C₁-C₁₂alkyl group bearing an electrophilic function such as an isothiocyanate;R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Hal where Halis Cl, Br, F or I; or an acetoxy group or a sulfonate ester group or anoxo group; or R₁₀ and R₁₁ may represent an isoalkylidene group; or

wherein R₁, R₂, R₃, R₅, R₆, R₇, R₈ and R₉ are defined as above, R₄ is Hor OH or OC_(l)H_(2l+1) with l between 2 and 6; R₁₀ is C_(y)H_(2y) withy between 1 and 12 or CH₂CH₂[OCH₂CH₂]_(z)OCH₂CH₂ with z between 0 and10; and R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Halwhere Hal is Cl, Br, F or I; or an acetoxy group or a sulfonate estergroup or an oxo group; and all stereoisomers and optical isomersthereof, with the proviso that in formula (I) (1) R₂ is not H or alcoxywhen R₃ is OH or alcoxy and R₄ is H or OH and R₅ and R₆ are OH oracyloxy and R₇ is OCH₃ and R₈ and R₉ represent a double bound and R₁,R₁₀ and R₁₁ are H; and (2) R₁ is not H when R₂ is H and R₃ and R₇ areOCH₃, R₄, R₅ and R₆ are OH and R₈ and R₉ represent a double bound andR₁₀ and R₁₁ are H.
 2. Chemical compound of claim 1 with formula (I). 3.Chemical compound of claim 1, wherein R₁₁ is OH.
 4. Chemical compound ofclaim 1, wherein R₈ and R₉ form a covalent bound.
 5. Chemical compoundof claim 1, wherein R₁₁ is OH and R₁ and R₂ are H.
 6. Chemical compoundof claim 1, wherein R₁₀ is H or C_(r)H_(2r)-A with r between 1 and 12and whereby A is H or a cycle C_(s)H_(2s−l) with s between 3 and 6 or anaromatic cycle or an aromatic polycycle or an aromatic cycle substitutedas C₆H_(5−t)-(Hal)_(t) with t between 1 to 5 and where Hal is Cl, Br, For I, or as C₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u between 1 to 5 and vbetween 0 to 6, or as C₆H_(5−w)—(NH₂)_(w) with w between 1 to 2; or R₁₀represents two substituents similar or different rendering the nitrogenatom quaternized, or an oxygen atom; or R₁₀ representsCH₂—CH₂—[O—CH₂—CH₂]_(x)O—CH₂—CH₂—B with x between 0 and 10 and whereby Bis H or OH or NH₂ or N═C═S.
 7. Chemical compound of claim 1, selectedfrom the group comprising4,6,7,10-tetrahydroxy-8,14-didehydro-3,8-dimethoxymorphinan andN-methyl-, N-propyl-, N-4-methoxybenzyl-, N-4-hydroxybenzyl-,N-4-bromobenzyl- or N-cyclopentyl--4,6,7,10-tetrahydroxy-8,14-didehydro-3,8-dimethoxy-morphinan. 8.Chemical compound of claim 7 having the optical configuration (6S, 7S,9R, 10R, 13S).
 9. Anti-malarial compound of formula

wherein R₁ is H or OC_(i)H_(2i+1) with i between 0 and 6; R₂ is H orOC_(j)H_(2j+1) with j between 0 and 6; R₃ is H or OC_(k)H_(2k+1) with kbetween 0 and 6; R₄ is H or OH; R₅ is OH or OC_(m)H_(2m+1) with mbetween 1 and 6 or an acetoxy group or an oxo group; R₆ is OH orOC_(n)H_(2n+1) with n between 1 and 6 or an acetoxy group or an oxogroup; R₇ is OC_(p)H_(2p+1) with p between 0 and 6; R₈ and R₉ may besimilar or different and represent H or OC_(q)H_(2q+1) with q between 0and 6, or Hal where Hal is Cl, Br, F or I, or form together a covalentbond whereby the bond is a double bond or an ether bond; R₁₀ is H orC_(r)H_(2r+1) with r between 1 and 12 or an unsaturated alkyl group or acycloalkyl group (tri- to hexa-) unsaturated or not, with or withoutheteroatoms; or an aromatic or a polycyclic aromatic group with orwithout heteroatoms; or C_(s)H_(2s)-A with s between 1 and 12 andwhereby A is a saturated or (tri- to hexa-) unsaturated cycloalkylgroup, with or without heteroatoms or an aromatic or a polycyclicaromatic group with or without heteroatoms or A is C₆H_(5−t)-(Hal)_(t)with t between 1 to 5 or C₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u between1 to 5 and v between 0 and 6; or R₁₀ represents two substituents similaror different rendering the nitrogen atom quaternized, or an oxygen atom(nitrone group) and in which case the bond between the nitrogen atom andC₉ is a double bond; or R₁₀ represents CH₂CH₂[OCH₂CH₂]_(w)OCH₂CH₂—B withw between 0 and 10 and where B is OH, O-D or NH-D where D is a C₁-C₁₂alkyl group bearing an electrophilic function such as an isothiocyanate;R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Hal where Halis Cl, Br, F or I; or an acetoxy group or a sulfonate ester group or anoxo group; or R₁₀ and R₁₁ may represent an isoalkylidene group; or

wherein R₁, R₂, R₃, R₅, R₆, R₇, R₈ and R₉ are defined as above, R₄ is Hor OH or OC_(l)H_(2l+1) with l between 2 and 6; R₁₀ is C_(y)H_(2y) withy between 1 and 12 or CH₂CH₂[OCH₂CH₂]_(z)OCH₂CH₂ with z between 0 and10; and R₁₁ is H or OH or OCxH2x+1 with x between 1 and 6 or Hal whereHal is Cl, Br, F or I; or an acetoxy group or a sulfonate ester group oran oxo group; and all stereoisomers and optical isomers thereof.
 10. Apharmaceutical composition comprising: an anti-malarial compound offormula 1

wherein R₁ is H or OC_(i)H_(2i+1) with i between 0 and 6; R₂ is H orOC_(j)H_(2j+1) with j between 0 and 6; R₃ is H or OC_(k)H_(2k+1) with kbetween 0 and 6; R₄is H or OH; R₅ is OH or OC_(m)H_(2m+1) with m between1 and 6 or an acetoxy group or an oxo group; R₆ is OH or OC_(n)H_(2n+1)with n between 1 and 6 or an acetoxy group or an oxo group; R₇ isOC_(p)H_(2p+1) with p between 0 and 6; R₈ and R₉ may be similar ordifferent and represent H or OC_(q)H_(2q+1) with q between 0 and 6, orHal where Hal is Cl, Br, F or I, or form together a covalent bondwhereby the bond is a double bond or an ether bond; R₁₀ is H orC_(r)H_(2r+1) with r between 1 and 12 or an unsaturated alkyl group or acycloalkyl group (tri- to hexa-) unsaturated or not, with or withoutheteroatoms; or an aromatic or a polycyclic aromatic group with orwithout heteroatoms; or C_(s)H_(2s)-A with s between 1 and 12 andwhereby A is a saturated or (tri- to hexa-) unsaturated cycloalkylgroup, with or without heteroatoms or an aromatic or a polycyclicaromatic group with or without heteroatoms or A is C₆H_(5−t)-(Hal)_(t)with t between 1 to 5 or C₆H_(5−u)—(O—C_(v)H_(2v+1))_(u) with u between1 to 5 and v between 0 and 6; or R₁₀ represents two substituents similaror different rendering the nitrogen atom quaternized, or an oxygen atom(nitrone group) and in which case the bond between the nitrogen atom andC₉ is a double bond; or R₁₀ represents CH₂CH₂[OCH₂CH₂]_(w)OCH₂CH₂—B withw between 0 and 10 and where B is OH, O-D or NH-D where D is a C₁-C₁₂alkyl group bearing an electrophilic function such as an isothiocyanate;R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Hal where Halis Cl, Br, F or I; or an acetoxy group or a sulfonate ester group or anoxo group; or R₁₀ and R₁₁ may represent an isoalkylidene group; or ananti-malarial compound of formula II

wherein R₁, R₂, R₃, R₅, R₆, R₇, R₈ and R₉ are defined as above, R₄ is Hor OH or OC_(l)H_(2l+1) with l between 2 and 6; R₁₀ is C_(y)H_(2y) withy between 1 and 12 or CH₂CH₂[OCH₂CH₂]_(z)OCH₂CH₂ with z between 0 and10; and R₁₁ is H or OH or OC_(x)H_(2x+1) with x between 1 and 6 or Halwhere Hal is Cl, Br, F or I; or an acetoxy group or a sulfonate estergroup or an oxo group; all stereoisomers and optical isomers thereof ofsaid formula I or formula II, and their pharmaceutically acceptablesalts.
 11. The pharmaceutical composition according to claim 10 furthercomprising at least one second anti-malarial compound; and apharmaceutically acceptable vehicle.
 12. The pharmaceutical compositionaccording to claim 11, wherein the compound of formula I or II ispresent in an amount of between 0.0019% and 50% by weight of thecomposition.
 13. The pharmaceutical composition according to claim 11,wherein the vehicle is aqueous.
 14. The pharmaceutical composition ofclaim 11, wherein said second anti-malarial compound is an isolatedextract of Strychnopsis thouarsii.
 15. A pharmaceutical compositioncomprising at least one compound as defined in claim 1, or theirpharmaceutically acceptable salts and a pharmaceutically acceptablevehicle.
 16. The pharmaceutical composition according to claim 15,wherein, the compound of formula I or II is present in an amount between0.001% and 50% by weight of the composition.
 17. A pharmaceuticalcomposition comprising an isolated extract of Strychnopsis thouarsiihaving an anti-malarial activity.
 18. A method for preventing malaria ina subject or treating a subject suffering from malaria comprising:administering to said subject an effective amount of the anti-malarialcompound according to claim
 9. 19. A method for preventing malaria in asubject or treating a subject suffering from malaria comprising:administering to said subject an effective amount of isolated extract ofStrychnopsis thouarsii.
 20. A method for treating a subject sufferingfrom hepatic stage malaria: administering to said subject an effectiveamount of the anti-malarial compound according to claim 9.